forked from syncthing/discosrv
/
main.go
392 lines (333 loc) · 8.01 KB
/
main.go
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// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
package main
import (
"bytes"
"encoding/binary"
"flag"
"fmt"
"io"
"log"
"net"
"os"
"path/filepath"
"sync"
"time"
"github.com/golang/groupcache/lru"
"github.com/juju/ratelimit"
"github.com/syncthing/protocol"
"github.com/syncthing/syncthing/lib/discover"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/opt"
)
const cacheLimitSeconds = 3600
var (
lock sync.Mutex
queries = 0
announces = 0
answered = 0
limited = 0
unknowns = 0
debug = false
lruSize = 1024
limitAvg = 1
limitBurst = 10
limiter *lru.Cache
)
func main() {
var listen string
var timestamp bool
var statsIntv int
var statsFile string
var unknownFile string
var dbDir string
flag.StringVar(&listen, "listen", ":22026", "Listen address")
flag.BoolVar(&debug, "debug", false, "Enable debug output")
flag.BoolVar(×tamp, "timestamp", true, "Timestamp the log output")
flag.IntVar(&statsIntv, "stats-intv", 0, "Statistics output interval (s)")
flag.StringVar(&statsFile, "stats-file", "/var/discosrv/stats", "Statistics file name")
flag.StringVar(&unknownFile, "unknown-file", "", "Unknown packet log file name")
flag.IntVar(&lruSize, "limit-cache", lruSize, "Limiter cache entries")
flag.IntVar(&limitAvg, "limit-avg", limitAvg, "Allowed average package rate, per 10 s")
flag.IntVar(&limitBurst, "limit-burst", limitBurst, "Allowed burst size, packets")
flag.StringVar(&dbDir, "db-dir", "/var/discosrv/db", "Database directory")
flag.Parse()
limiter = lru.New(lruSize)
log.SetOutput(os.Stdout)
if !timestamp {
log.SetFlags(0)
}
addr, _ := net.ResolveUDPAddr("udp", listen)
conn, err := net.ListenUDP("udp", addr)
if err != nil {
log.Fatal(err)
}
parentDir := filepath.Dir(dbDir)
if _, err := os.Stat(parentDir); err != nil && os.IsNotExist(err) {
err = os.MkdirAll(parentDir, 0755)
if err != nil {
log.Fatal(err)
}
}
db, err := leveldb.OpenFile(dbDir, &opt.Options{OpenFilesCacheCapacity: 32})
if err != nil {
log.Fatal(err)
}
statsLog, err := os.OpenFile(statsFile, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
if err != nil {
log.Fatal(err)
}
var unknownLog io.Writer
if unknownFile != "" {
unknownLog, err = os.OpenFile(unknownFile, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
if err != nil {
log.Fatal(err)
}
}
if statsIntv > 0 {
go logStats(statsLog, statsIntv)
}
go clean(statsLog, db)
var buf = make([]byte, 1024)
for {
buf = buf[:cap(buf)]
n, addr, err := conn.ReadFromUDP(buf)
if limit(addr) {
// Rate limit in effect for source
continue
}
if err != nil {
log.Fatal(err)
}
if n < 4 {
log.Printf("Received short packet (%d bytes)", n)
continue
}
buf = buf[:n]
magic := binary.BigEndian.Uint32(buf)
switch magic {
case discover.AnnouncementMagic:
err := handleAnnounceV2(db, addr, buf)
if err != nil && unknownLog != nil {
fmt.Fprintf(unknownLog, "AE %d %v %x\n", time.Now().Unix(), addr, buf)
}
case discover.QueryMagic:
err := handleQueryV2(db, conn, addr, buf)
if err != nil && unknownLog != nil {
fmt.Fprintf(unknownLog, "QE %d %v %x\n", time.Now().Unix(), addr, buf)
}
default:
lock.Lock()
unknowns++
lock.Unlock()
if unknownLog != nil {
fmt.Fprintf(unknownLog, "UN %d %v %x\n", time.Now().Unix(), addr, buf)
}
}
}
}
func limit(addr *net.UDPAddr) bool {
key := addr.IP.String()
lock.Lock()
defer lock.Unlock()
bkt, ok := limiter.Get(key)
if ok {
bkt := bkt.(*ratelimit.Bucket)
if bkt.TakeAvailable(1) != 1 {
// Rate limit exceeded; ignore packet
if debug {
log.Println("Rate limit exceeded for", key)
}
limited++
return true
}
} else {
if debug {
log.Println("New limiter for", key)
}
// One packet per ten seconds average rate, burst ten packets
limiter.Add(key, ratelimit.NewBucket(10*time.Second/time.Duration(limitAvg), int64(limitBurst)))
}
return false
}
func handleAnnounceV2(db *leveldb.DB, addr *net.UDPAddr, buf []byte) error {
var pkt discover.Announce
err := pkt.UnmarshalXDR(buf)
if err != nil && err != io.EOF {
return err
}
if debug {
log.Printf("<- %v %#v", addr, pkt)
}
lock.Lock()
announces++
lock.Unlock()
ip := addr.IP.To4()
if ip == nil {
ip = addr.IP.To16()
}
var addrs []address
now := time.Now().Unix()
for _, addr := range pkt.This.Addresses {
tip := addr.IP
if len(tip) == 0 {
tip = ip
}
addrs = append(addrs, address{
ip: tip,
port: addr.Port,
seen: now,
})
}
var id protocol.DeviceID
if len(pkt.This.ID) == 32 {
// Raw node ID
copy(id[:], pkt.This.ID)
} else {
err = id.UnmarshalText(pkt.This.ID)
if err != nil {
return err
}
}
update(db, id, addrs)
return nil
}
func handleQueryV2(db *leveldb.DB, conn *net.UDPConn, addr *net.UDPAddr, buf []byte) error {
var pkt discover.Query
err := pkt.UnmarshalXDR(buf)
if err != nil {
return err
}
if debug {
log.Printf("<- %v %#v", addr, pkt)
}
var id protocol.DeviceID
if len(pkt.DeviceID) == 32 {
// Raw node ID
copy(id[:], pkt.DeviceID)
} else {
err = id.UnmarshalText(pkt.DeviceID)
if err != nil {
return err
}
}
lock.Lock()
queries++
lock.Unlock()
addrs := get(db, id)
now := time.Now().Unix()
if len(addrs) > 0 {
ann := discover.Announce{
Magic: discover.AnnouncementMagic,
This: discover.Device{
ID: pkt.DeviceID,
},
}
for _, addr := range addrs {
if now-addr.seen > cacheLimitSeconds {
continue
}
ann.This.Addresses = append(ann.This.Addresses, discover.Address{IP: addr.ip, Port: addr.port})
}
if debug {
log.Printf("-> %v %#v", addr, pkt)
}
if len(ann.This.Addresses) == 0 {
return nil
}
tb, err := ann.MarshalXDR()
if err != nil {
log.Println("QueryV2 response marshal:", err)
return nil
}
_, err = conn.WriteToUDP(tb, addr)
if err != nil {
log.Println("QueryV2 response write:", err)
return nil
}
lock.Lock()
answered++
lock.Unlock()
}
return nil
}
func next(intv int) time.Time {
d := time.Duration(intv) * time.Second
t0 := time.Now()
t1 := t0.Add(d).Truncate(d)
time.Sleep(t1.Sub(t0))
return t1
}
func logStats(statsLog io.Writer, intv int) {
for {
t := next(intv)
lock.Lock()
fmt.Fprintf(statsLog, "%d Queries:%d Answered:%d Announces:%d Unknown:%d Limited:%d\n",
t.Unix(), queries, answered, announces, unknowns, limited)
queries = 0
announces = 0
answered = 0
limited = 0
unknowns = 0
lock.Unlock()
}
}
func get(db *leveldb.DB, id protocol.DeviceID) []address {
var addrs addressList
val, err := db.Get(id[:], nil)
if err == nil {
addrs.UnmarshalXDR(val)
}
return addrs.addresses
}
func update(db *leveldb.DB, id protocol.DeviceID, addrs []address) {
var newAddrs addressList
val, err := db.Get(id[:], nil)
if err == nil {
newAddrs.UnmarshalXDR(val)
}
nextAddr:
for _, newAddr := range addrs {
for i, exAddr := range newAddrs.addresses {
if bytes.Compare(newAddr.ip, exAddr.ip) == 0 {
newAddrs.addresses[i] = newAddr
continue nextAddr
}
}
newAddrs.addresses = append(newAddrs.addresses, newAddr)
}
db.Put(id[:], newAddrs.MarshalXDR(), nil)
}
func clean(statsLog io.Writer, db *leveldb.DB) {
for {
now := next(cacheLimitSeconds)
nowSecs := now.Unix()
var kept, deleted int64
iter := db.NewIterator(nil, nil)
for iter.Next() {
var addrs addressList
addrs.UnmarshalXDR(iter.Value())
// Remove expired addresses
newAddrs := addrs.addresses
for i := 0; i < len(newAddrs); i++ {
if nowSecs-newAddrs[i].seen > cacheLimitSeconds {
newAddrs[i] = newAddrs[len(newAddrs)-1]
newAddrs = newAddrs[:len(newAddrs)-1]
}
}
// Delete empty records
if len(newAddrs) == 0 {
db.Delete(iter.Key(), nil)
deleted++
continue
}
// Update changed records
if len(newAddrs) != len(addrs.addresses) {
addrs.addresses = newAddrs
db.Put(iter.Key(), addrs.MarshalXDR(), nil)
}
kept++
}
iter.Release()
fmt.Fprintf(statsLog, "%d Kept:%d Deleted:%d Took:%0.04fs\n", nowSecs, kept, deleted, time.Since(now).Seconds())
}
}